Attachment Blocking

Outlook 2000SR1 introduced a new security feature to block attachments which were considered unsafe. Ever since Outlook 2002 that feature has been standard. If you receive an e-mail message that contains one of the blocked file types, you may receive the following warning message:

Outlook blocked access to the following potentially unsafe attachments: [...]

Although Outlook has blocked access to the attachment, the attachment still exists in the message. There are numerous Knowledge Base articles available from Microsoft which summarize what to do if you must open the attachment.

829982 You cannon open attachments in Outlook 2003

Q290497 OL2002: You Cannot Open Attachments

Q318515 OL2000: Cannot Access Attachments

The articles provide a procedure for editing the registry on the client workstation to include or exclude certain file types from the list of dangerous file types which are blocked.

Please note, this has little to do with the Exchange server. The server has not blocked access to your attachment, Outlook has.

Add a registry string value under HKEY_CURRENT_USER\Software\Microsoft\Office\<VERSION>\Security called Level1Remove and add the extensions you want with leading dots and trailing semicolons like:

.pst;.rar